A federal judge in Washington ruled on Monday that the bulk collection of Americans' telephone records by the National Security Agency is likely to violate the US constitution, in the most significant legal setback for the agency since the first disclosures prompted by the whistleblower Edward Snowden.

Judge Richard Leon declared that the mass collection of metadata probably violates the fourth amendment, which prohibits unreasonable searches and seizures, and was "almost Orwellian" in its scope. In a judgment replete with literary swipes against the NSA, he said James Madison, the architect of the US constitution, would be "aghast" at the scope of the agency’s collection of Americans' communications data.

It's just a preliminary ruling, and while the judge stated that he would most likely uphold the preliminary ruling after the merits of the case have been handled, there's probably thousands of appeals and stuff like that where this could crumble into dust.

Once a government has obtained a power, it rarely releases it. That's the nature of government - it can only grow.